Conventionally, as an example of this type of blood pressure measurement cuff, there is known to be a fold-back type of blood pressure measurement cuff (armband), such as that disclosed in Patent Document 1 (JP H08-215159A). As illustrated in FIG. 19A, a cuff 100 includes an oval-shaped fold-back fitting 106 near one end 104e in a length direction of an outer cloth (surface cloth) 104 of the cuff 100, and includes a hook-and-loop fastener (engagement portion) 103 near another end (leading end) 104f in the length direction of the outer cloth 104. An air bladder 102 (see FIG. 18D) is contained between the outer cloth 104 and an inner cloth (underside cloth) 105 of the cuff 100. Also, in this example, a microphone 101 for observing a pulse sound is included at a portion approximately in the center in the length direction.
During attachment, as illustrated in FIG. 19A, the cuff 100 is first made cylindrical by passing the leading end portion 104f through the ring-shaped fold-back fitting 106 with the outer cloth 104 of the cuff facing outward. Next, a left arm 90 serving as a measurement site is passed through the cylindrical cuff from a side at which the cylindrical cuff appears to the measurement subject to be in the form of a clockwise spiral (note that FIGS. 19A and B illustrate cross-sectional views of the left arm 90 as viewed from the measurement subject), and the left arm 90 is adjusted so that the microphone 101 is located almost on an artery 90P when the palm of the hand has been turned upward. Next, the leading end portion 104f is pulled leftward as indicated by arrow A1 so that a gap between the inner cloth 105 of the cuff and the left arm 90 is mostly eliminated. Thereafter, as illustrated in FIG. 19B, a portion continuous with the leading end portion 104f of the cuff is folded back as indicated by arrow B1 from the position of the fold-back fitting 106 and the hook-and-loop fastener 103 is fixed to an opposing portion 104x on the outer cloth 104. Thus, the cuff 100 is attached to the left arm 90 serving as the measurement site. Note that arrow A2 in FIG. 19A and arrow B2 in FIG. 19B each indicate tension acting on the cuff.
In this state, air is pumped into or evacuated from the air bladder 102 through an air tube using a pump, and based on the pulse sound observed using the microphone 101, the blood pressure is measured (Korotkoff method). Note that instead of using the Korotkoff method, the blood pressure can be measured using the oscillometric method (the cuff itself detects change in a pulse wave as a pressure sensor) as well.